The objective of this proposal is to produce a panel of stable conformational isomers of human a- synuclein (aSyn) for use as immunogens to develop immunotherapy of Parkinson disease (PD). Human a-Synuclein (a-Syn) is a recognized protein marker for the potential intervention of PD. Immunotherapy targeting the clearance of aSyn aggregates was shown to be a promising approach for PD treatment [Masliah et al., 2005]. This ground breaking study points out substantial opportunities for developing more potent and versatile aSyn immunogen. In this proposal, we will take the approach of using stabilized conformational isomers of aSyn (collectively termed as X-aSyn) to enhance its immunogenicity and provide new epitopes for aSyn immunotherapy. Our laboratory has developed a novel technology for stabilizing and purifying non-native protein conformational isomers (X-isomers) [Chang and Li, 2001] that have potential as antigens for generating therapeutic antibodies against "self" antigens. This innovative technology has three important advantages: 1) it produces conformational isomers in a controlled environment;2) it stabilizes the isomers chemically so they can be evaluated in vivo and in vitro;and 3) it breaks immune tolerance and allows the production of antibodies against endogenous proteins. Preliminary studies with other model proteins demonstrated that such stabilized non-native isomers are capable of breaking the immune tolerance. They are immunogenic in mice and elicit anti-X-isomer antibodies cross-react with the native protein. The specific aims are: 1) To generate and isolate a panel of conformational isomers of wt-aSyn, which are stabilized by 2 and 3 synthetic disulfide bonds (collectively termed X-aSyn);2) To determine the relative immunogenicity of isomers of X-aSyn and (wild-type) N-aSyn in transgenic mice expressing human aSyn and to demonstrate that X-aSyn can be used to raise high-titer antibodies that cross react with N-aSyn;and 3) To evaluate the neuronal accumulation of aSyn aggregates and neuro-degeneration in transgenic mice immunized with isomers of X-aSyn and (wild-type) N-aSyn. Successful completion of these aims will lead to the identification and production of isomers of X-aSyn as immunogens for developing active and passive immunotherapy of PD. PUBLIC HEALTH RELEVANCE: The long-term goal of this research program is to develop therapeutic vaccines targeting reduction and clearance of a-Synuclein (aSyn) for treatment of Parkinson Disease (PD). Our lab has developed an innovative technology to produce novel conformational isomers of aSyn that are chemically stable and immunogenic. Successful completion of this project will generate lead aSyn isomers, effective in PD transgenic mouse model, for further development as therapeutic vaccine in treatment of PD.